[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical skills](https://durgical.com/en/clinical-skills/) › [Airway and cardiac procedures](https://durgical.com/en/clinical-skills/areas/airway-cardiac/) › Starting non-invasive ventilation

# Starting non-invasive ventilation

- Procedure

A tight mask and a machine push air into the lungs to help a tired patient breathe, without putting a tube down the throat.

Updated Nov 13, 2026

## Key points

- Best evidence: COPD exacerbation with respiratory acidosis despite medical treatment, and acute cardiogenic pulmonary oedema.
- CPAP mainly improves oxygenation; bilevel NIV (IPAP over EPAP) also improves ventilation and clears CO2.
- Decide and document the escalation plan (intubation or ceiling of care) before starting.
- Recheck the blood gas within about 1–2 hours; failure to improve means escalation.
- Contraindications include respiratory arrest, inability to protect the airway, vomiting, facial trauma and an undrained pneumothorax.

On this page

- The basics Key points
- What it is
- Indications
- Equipment
- Step by step (and why)
- CPAP and bilevel NIV: what each pressure does.
- Next step
- Elsewhere in DurgiPedia

- Clinical Complications

- Safety Contraindications and precautions

- Study Test yourself

- Connections Connections

## What it is

Non-invasive ventilation (NIV) gives positive airway pressure through a tight-fitting mask instead of a tracheal tube. Continuous positive airway pressure (CPAP) keeps one pressure throughout the breath: it holds collapsed alveoli open, improves oxygenation and, in heart failure, lowers preload and left ventricular afterload. Bilevel ventilation (often called BiPAP) alternates a higher inspiratory pressure (IPAP) with a lower expiratory pressure (EPAP). The difference between them is the pressure support that enlarges each breath and washes out carbon dioxide; EPAP, like CPAP, recruits alveoli, improves oxygenation and offsets intrinsic PEEP in COPD. The strongest evidence is for acute hypercapnic respiratory failure in COPD exacerbations and for acute cardiogenic pulmonary oedema, where NIV reduces the need for intubation and death. It is also used in obesity hypoventilation, neuromuscular disease, chest wall disease and selected immunocompromised patients, and as a ceiling of treatment. Before starting, decide and record what happens if NIV fails: intubation, or NIV as the ceiling of care. Pressures and oxygen are started and then titrated as local protocols set, guided by comfort, breathing pattern, saturation and blood gases. The first hour decides most cases: no improvement in pH, carbon dioxide or work of breathing means escalation, not waiting.

## Indications

- Acute exacerbation of COPD with hypercapnic respiratory acidosis that persists despite optimal medical treatment.
- Acute cardiogenic pulmonary oedema with respiratory distress (CPAP or bilevel).
- Obesity hypoventilation, neuromuscular disease and chest wall deformity with hypercapnic respiratory failure.
- Selected immunocompromised patients with hypoxaemic respiratory failure, and selected patients after extubation.
- Patients for whom NIV is the agreed ceiling of treatment, including palliative relief of breathlessness.

## Contraindications and precautions

- Respiratory or cardiac arrest, or a need for immediate intubation.
- Cannot protect the airway: reduced consciousness (except hypercapnic drowsiness under close watch), vomiting, copious secretions.
- Facial trauma, burns or deformity, or recent facial, upper airway or upper gastrointestinal surgery.
- Undrained pneumothorax, haemodynamic instability, bowel obstruction or severe agitation.
- Asthma, pneumonia and ARDS: use only with experience and a low threshold for intubation, in a monitored area.

## Equipment

- NIV-capable ventilator with oxygen supply, circuit, filter and humidification as needed.
- Interfaces in several sizes: full-face (oronasal) mask first in acute illness; nasal mask or helmet as alternatives.
- Sizing gauge, headgear and dressings to protect the bridge of the nose.
- Continuous pulse oximetry, ECG and blood pressure monitoring; arterial blood gas sampling kit.
- Equipment and staff for intubation available nearby.

## Step by step (and why)

- Confirm the indication with a blood gas, start medical treatment and record the escalation plan — NIV failure must have a next step.
- Explain the mask and the air pressure to the patient and agree a signal — fear and claustrophobia cause most early failures.
- Sit the patient up and choose a full-face mask of the right size with the gauge — the right size seals without overtightening.
- Hold the mask on the face before strapping it — this lets the patient get used to the airflow.
- Start at low pressures and titrate up over minutes, as local protocols set — rapid high pressures are poorly tolerated.
- Raise EPAP (or CPAP) for oxygenation and the IPAP–EPAP gap for CO2 — EPAP recruits alveoli; pressure support enlarges breaths.
- Add oxygen to the target saturation (often 88–92% in hypercapnic COPD) — too much oxygen worsens CO2 retention.
- Fit the headgear with a small leak allowed (two fingers under the straps) and protect the nasal bridge — tight straps cause ulcers.
- Watch synchrony, leak, rate, saturation and comfort, and repeat the blood gas within 1–2 hours — this decides success or escalation.

## CPAP and bilevel NIV: what each pressure does.

| Pressure | What it does | Raise it to improve |
| --- | --- | --- |
| CPAP | One continuous pressure; holds alveoli open, lowers preload and afterload | Oxygenation (pulmonary oedema) |
| EPAP | Expiratory pressure; recruits alveoli, offsets intrinsic PEEP | Oxygenation; triggering in COPD |
| IPAP | Inspiratory pressure; IPAP minus EPAP is the pressure support | Ventilation: tidal volume and CO2 clearance |

## Complications

- Pressure ulcers on the bridge of the nose and facial skin from the mask.
- Air leaks causing eye irritation, conjunctivitis and patient–ventilator asynchrony.
- Gastric distension, vomiting and aspiration.
- Hypotension from reduced venous return, especially when the patient is hypovolaemic.
- Pneumothorax, dry mouth and nose, claustrophobia, and delayed intubation when failure is not recognised.

## Next step

- Improving pH, CO2, rate and comfort: continue NIV for as long as possible in the first day, then wean as local protocols set.
- No improvement or worsening at the 1–2 hour gas, falling consciousness or exhaustion: call the senior or ICU team to intubate.
- If NIV is the ceiling of care and fails, change the focus to comfort and symptom relief with the patient and family.
- Check the skin under the mask, mouth care and secretions regularly, and plan breaks for meals and medication.
- Treat the cause in parallel (bronchodilators, steroids, antibiotics, diuretics) and consider long-term home NIV before discharge.

## Test yourself

Think of the answer, then tap the question to see it.

## In which two acute conditions is the evidence for non-invasive ventilation strongest?

COPD exacerbation with hypercapnic respiratory acidosis despite medical treatment, and acute cardiogenic pulmonary oedema; in both, NIV lowers intubation rates and mortality.

## What is the difference between the roles of IPAP and EPAP in bilevel ventilation?

EPAP keeps alveoli open and improves oxygenation (and offsets intrinsic PEEP); the gap between IPAP and EPAP is the pressure support that enlarges breaths and clears carbon dioxide.

## What must be decided and documented before starting non-invasive ventilation?

The escalation plan: whether the patient would be intubated if NIV fails, or whether NIV is the ceiling of treatment, agreed with the patient or family where possible.

## When should non-invasive ventilation be judged to be failing?

When pH and carbon dioxide do not improve or worsen on the blood gas within about 1–2 hours, or consciousness falls or work of breathing rises; then escalate to intubation or palliation.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/clinical-skills/starting-non-invasive-ventilation/)

## Elsewhere in DurgiPedia

- [Hypoxemic and hypercapnic respiratory failure](https://durgical.com/en/physiology/hypoxemic-and-hypercapnic-respiratory-failure/)
- [The work of breathing](https://durgical.com/en/physiology/the-work-of-breathing/)
- [Respiratory acidosis and alkalosis](https://durgical.com/en/physiology/respiratory-acidosis-and-alkalosis/)
- [Oxygen therapy: devices, flows and safety](https://durgical.com/en/nursing/oxygen-therapy-devices-flows-and-safety/)

## Connections

## Related 4

- [Arterial blood gas sampling and the Allen test](https://durgical.com/en/clinical-skills/arterial-blood-gas-sampling-and-the-allen-test/)
- [Arterial blood gas: worked cases for the station](https://durgical.com/en/clinical-skills/arterial-blood-gas-worked-cases-for-the-station/)
- [Bag-mask ventilation](https://durgical.com/en/clinical-skills/bag-mask-ventilation/)
- [Peak flow and inhaler technique](https://durgical.com/en/clinical-skills/peak-flow-and-inhaler-technique/)

## Related conditions 5

- [Chronic obstructive pulmonary disease (COPD)](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Acute respiratory failure (hypoxaemic and hypercapnic)](https://durgical.com/en/conditions/acute-respiratory-failure/)
- [Obesity hypoventilation syndrome](https://durgical.com/en/conditions/obesity-hypoventilation-syndrome/)
- [Obstructive sleep apnoea](https://durgical.com/en/conditions/obstructive-sleep-apnoea/)

## In Pharmacology 1

- [Oxygen](https://durgical.com/en/pharmacology/oxygen/)

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Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: [Noninvasive Ventilation](https://www.ncbi.nlm.nih.gov/books/NBK578188/) (StatPearls (NCBI Bookshelf), 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-skills/starting-non-invasive-ventilation/